Contactors



United States Patent CONTACTORS Joseph J. Gribble, Fox Point, Wis.,assignor to Square D Company, Detroit, Mich., a corporation of MichiganApplication September 14, 1955, Serial No. 534,227 2 Claims. (Cl.200-144) g The present invention relates to contactors and moreparticularly to contactors having a relatively high capacity requiringarcing barriers between two or more adjacent poles.

An object of the present invention is the provision of a contactorhaving an increased current interrupting capacity.

Another object is to provide a yoke or movable contact support meanswhich increases the 'current interrupting capacity of a contactor.

A further object of the invention is the provision of double breakcontact structure in which arcing is produced at one point which isenclosed by a cover block utilizing a minimum amount of material.

Still another object is to provide a contactor having the foregoingqualities and convertible from normally open position to a normally'closed position.

Further objects and features of the invention will be readily apparentto those skilled in the art from the specification and appended drawingillustrating certain preferred embodiments in which:

Figure 1 is a front view of the contactor partially in section of apreferred embodiment of the invention.

Figure 2 is a cross sectional view of the contactor taken along the line22 of Figure 1 in the direction shown.

Figure 3 shows a section of the contactor taken along the line 3-3 ofFigure 1 in the direction indicated.

Figure 4 is a pictorial view of the cover block.

Referring now to the drawings, wherein like reference charactersdesignate like or corresponding parts throughout the several views,there is shown in Figures 1 to 3 which illustrate a preferredembodiment, a contactor 6 supported on a mounting plate 8. The contactoris a modified .form of an air circuit breaker requiring an auxiliarysource of power or apparatus, e. g., solenoid or latching means forholding the contactor in closed position. The principal parts of thecontactor include an insulating base, contact operating means, and thecontacts which coact to complete or to interrupt a circuit. Thecontactor section includes a double break contact structure having apair of stationary contacts or brackets '9 and 10 mounted in opposingrelation to a movable contact bridge 12 having a pair of correspondingcontact sections on a supporting strap. The stationary contacts orbrackets 9 and 10 are mounted on an insulating base block 13 in arcchutes or chambers 14 by means of terminal straps 15,16 and secured tothe insulating block 13 by screws 17 and A four pole contactor has beenillustrated in which the section taken along section line 2 and shown inFigure 2 discloses a normally closed contact; and the cross sectiontaken along the line 3 shown in Figure 3 discloses a normally opencontact structure.

' Referring more particularly to Figure 3, in which the normally open'contacts are shown; a double break ice circuit interrupter is shownhaving L-shaped stationary contact brackets 19 and 20 mounted on theinsulating base block 13 in the arc chute or chamber 22. The contacts onthe stationary brackets 19 and 20 are located in opposing relation tocontacts on the movable bridge 23 formed from a section of conductivestrap which completes the circuit between the line and loadstationarycontacts of the contact support straps 19 and 20 respectively.The stationary contact support straps are secured in position byterminal straps 26 and 27 which are fastened to the insulating block 13by screws 17 and 18. Since the contacts are subject to wear suitablefastening means such as screws 24 and 25 are provided for removablyattaching the contact straps to the terminal straps 26 and 27. l Themovable bridge is also subject to wear and replacement and is thereforeremovably retained in position by a movable contact operator or springguide 28 and helical spring 29 which are mounted on the yoke 30 andsecured to an abutment thereon by a screw 33. On the ends of theterminal straps 26 and 27, load and line terminals 34 and 35,respectively, are provided, and suitably positioned for convenientaccess from the outside of the' insulating block 13.

In comparing the normally closed pole illustrated in Figure 2, and thenormally open pole in Figure 3, it is found that the load terminalstraps 15 and 26 are identical. However, the load contact support straps19 and 20 differ in length of the supporting legs and location of thecontacts to provide an opposing contact surface for the movable bridgecontacts. In the nor mally closed structure of Figure 2, the movablebridge 12 is biased against the stationary contacts by a helical spring37 which seats'on a suitable abutment provided on the insulating block13 in the upper part of the chamber directly above the spring guide 28.

The line contact bracket 10 is connected to the terminal strap 16 andhas an extension projecting into the chamber and a contact on the uppersurface which is disposed in opposing relation to the correspondingmovable bridge contact, cooperating with the load contact to staticallyload the spring 37 and position the bridge 12 across the stationarycontacts, and thereby incorporate a double break circuit structure. Theterminal strap 16 extends upwardly and out of the arc chute 14,projecting into an open chamber for the line terminals 38betweenbarriers 39 separating the poles of the contactor 6.

Referring to the normally open pole of the contactor shown inFigure 3,it is seen that the movable bridge is supported below the stationarycontacts by the spring guide 28, providing a contact gap betweenstationary and movable contacts and a spring 29 compressed uponenergization of the contact operating means shown in Figures 1 and 2.The L-shaped stationary contact strap 19 is positioned in a channel 40in the insulating block 13 and fastened to the line terminal strap 27which extends laterally into a terminal chamber 43 bounded on eitherside by are barriers 39 separating the line terminals from the adjacentpoles.

An L-shaped insulating block 13 is provided having arc chutes orchambers 14, 22, 31 and 32 and terminal chambers 43 housing the contactand terminal structure of the respective poles.

The contacts are mounted on the base block in the arc chutes or chamberswhich serve to confine an arc and separate the poles from each otherthereby minimizing the danger of striking an arc from one pole to thecontact structure of another pole and short circuiting the respectivelines. The insulating block 13 is made from are resisting insulatingmaterial wherein the arc extinction takes place as a result ofextensionof the are along the surface of the arc chute or cavity. Metalinserts may be molded in the arc chute to assist in extinguishing thearcj-and-"a certain amount of arc blowout is obtained 'bytheconfiguration of the line contacts of Figure 3 due to the magneticfield setup about the conductors tending to stretch the arc and force itagainst the walls of the chute thereby enhancing the cooling efiect.

The leg of the L-shaped base block forming chambers or are chutes 14,22', 31 and 32 is placed against the mounting plate 8 and includes aback surface 44 for securing the load straps and stationary contactstraps, closing the end of the chamber of the are chute and insulatingthe conducting parts from the mounting plate. The are barriers '39project laterally from the back sur face 44, the upper portion formingthe other leg of the L along with the portion of the block connectingthe arc barriers and serving as a base for mounting the terminal straps.As shown in Figures 2- and 3, vertical slots 45 and 46' are formed inthe portions of the block connecting' barriers 39, permitting theterminal straps or contact brackets to project from the chamber andexternal access to terminals 25 and 34.

In order to confine an are forming during the interruption of the frontor line contacts, a removable cover block 47 is secured over the openend of the chambers 14, 22, 31 and 32 to confine the ionization causedby the arcing of the contacts, and wherein the vertical barriers 48along with the vertical longitudinal front and bottom walls 49 and 50form individual" cavities for each pole. The'cov'er plate. is secured tothe vertical barriers by means of screws 52 extending through barriers48' of the cover plate and seating in threaded openings provided in thebarriers '39 along the adjacent vertical leg of the insulating block 13.

Under heavy current use the cover plate of the conta'ctor 6 is made of.tie-ionizing material which acts to accelerate the de-ionization of thegases formed in the cavity. In comparison with the insulating materialsused in the insulating block 13, the de-ionizing material used in thecover plate 4-7 is much morecostly. Since the deionizing eifect occursonly adjacent to the arc and is required only at the line contacts wherethe most severe arc occurs, the ale-ionizing material should only embodythe cavities adjacent the line contacts to encompass the are formedduring contact interruption.

The bottom wall 50 is cut back from the end of the arc barriers 48 andextends forward along the center line of the arc chamber forming slotsadjacent to the barriers to accommodate the yoke arc barriers 21. Openchannels are formed in the ends of the arc barriers to mate with the endflanges or abutments of the arc barriers of the insulating base block.13. As illustrated in Figures 2 and 3, the cavity forms a semi-circlealong the cross section to provide a continuous surface for the areformed between the contact bridge 23 and the stationary line contact, ofthe bracket 19.

The operating means is shown in Figures 1 and 2 and comprises anE-shaped stationary magnet 55 secured to the mounting plate 8; a coil56, positioned around the center projection having control or energizingterminals 57; and an armature 58 entirely outside the coil and movableagainst the striking surface 59 of the core or stationary magnet 55. AU-shaped actuating beam 60 is pivotally connected to the armature -3 bya pivot pin 61 at the lower end thereof and adapted to ride along thesurface of a support or retaining bracket 62 under the influence of themovement of the armature 58. The yoke 30' is secured tothe upper end ofthe beam 60 and includes a plurality of yoke arc barriers, one of eachbeing adjacent either transverse side of spring guides 28 except theoutside guide which has only one insulating barrier, to isolate theionization formed during an interrupting period from adjacent chambersand insulate 4 the bridge contact and spring guide from the adjacentpole for the length of travel of the yoke.-

The primary function of the yoke 30 is to actuate the movable contactstructure and couple the contact operators or guides 28 to the armature58 or actuating beam 60. The operating means is retained in position bythe retaining bracket 62 having-a slotted end portion slidablypositioned over a downwardly projecting member 42 integral with theactuating beam 60. As shown in Figure 2 the upper end of'the retainingbracket includes a vertical projecting flange seating in a slot formedin the under surfaceof theyoke30. The bracket 62 may be detached fromthe actuating beam or operating means by moving the bracket downwardlyuntil the'respective slots are disengaged. The operating means oractuating beam 69 is retained in operating position by the bracket 62wherein said bracket remains stationary and is secured by screws 63which are threaded into openings provided in the adjacent leg of thestationary magnet 55.

Operation The normally closed contacts of Figure 2 are opened uponenergization of the coil 56 attracting the armature 58 which strikesthesealing surface 59 of the core 55; moving the actuating beam 62, yoke30 and the spring guide 28 vertically a distance equal to the gapbetween the armature and stationary magnet. The spring guide strikes thebridge contact compressing the spring 37 opening the circuit between theline and. load contacts: Upon de' energization. of the coil. 56;, thearmature; and remainder of the operating means including the springguide 28, resumes the position shown in Figure 2 closing the circuitbetween the line and the-load.

The normally open contacts structure of Figure 3- may be closed in asimilar manner as described in the opening of the contacts in Figure 2,however in this instance the bridge contact 23 is retained by' thespring guide 28, and upon energizing of the coil and subsequentmovementof the armature; the spring guide and the bridge contacts move upwardlyin. a vertical direction closing the corresponding contacts between themovable bridge and stationary line and load contact straps.

During a circuit interruption period an are formed et-ween. the linecontact and the opposing movable contact on the contact bridge 23 isextinguished by being blowninto cavity. 54along the surface thereof andin addition, if the cover is made of de-ionizing material, the heat ofthe arc will partially decompose the surface of the material combiningwith, the gases formed to deionize the area adjacent the contacts.

While certain preferred embodiments ofthe invention have beenspecifically disclosed, it is understood that the invention is notlimited thereto, as many variations will be readily apparent to thoseskilled in the. art and the invention is. to be given its broadestpossible inter;- pretation within, the terms of the following claims.

What is claimed is:

1. In a contactor of the character described, the combinationcomprising; an insulating base providing a sup.- port for spaced pairsof stationary line and load contacts, a movable contact for each pair ofline and load contacts arranged for engagement therewith, meansincluding an insulating yoke for moving said movable contacts into andfrom engagement With the stationary line and load contacts, a separateinsulating block securable to said base said separable block beingformed of deionizing material, said block having a substantially fiatbottom surface with slots therein arranged to provide spaced separatedinternal chambers for enclosing the. line contacts and providing anopening for exposing the. load contacts and'an arcuate wall insaidchambers arranged for directing ionizing gases. away from the linecontacts and from said chamber when the movable contacts move fromengagement therewith and spaced barriers on the 5 yoke arranged forextending through the slots for directing the ionizing gases fromadjacent line contacts.

2. In a contactor of the character described, the combinationcomprising; an insulating base providing a support for a plurality ofpairs of exposed stationary line and load contacts which are arranged onthe support so the line contacts are laterally spaced on the support, amovable contact member including a yoke of insulating material carryingmovable contacts arranged to provide a bridging engagement between therespective parts of line and load contacts, a separate insulating blocksecurable to the base having spaced chambers therein arranged forenclosing and separating the line contacts from each other and toprovide an opening for permitting the load contacts to remainsubstantially exposed, said separate insulating block being formed ofde-ionizing material and the said chambers therein being constructedReferences Cited in the tile of this patent UNITED STATES PATENTS2,304,972 Van Valkenburg et a1. Dec. 15, 1942 2,319,906 Rowe May 25,1943 2,394,090 McFarland Feb. 5, 1946 2,448,659 Aitken Sept. 7, 19482,492,726 Ayers et al. Dec. 27, 1949 2,773,948 Pelz et a1. Dec. 11, 1956

